1. Field of the Invention
This invention relates to a terminal press-fitting construction including terminal press-fitting open holes, formed in a connector housing, and terminals inserted respectively in the terminal press-fitting open holes in a press-fitted manner.
2. Related art
A terminal press-fitting construction of the type described will be described with reference to FIG. 8.
A connector 1 includes connector housing 2, and male terminals 3 each having a round pin-shaped distal end portion 3a and a press-fitting portion 3b. In this terminal press-fitting construction, the male terminal 3 is press-fitted liquid-tight into a terminal press-fitting open hole 5 formed through an inner wall 4 of the connector housing 2.
After the male terminal 3 is thus press-fitted, a potting resin 7 is filled in a tubular potting cup 6 formed on a rear side of the inner wall 4, and the distal end portion 3a of the male terminal 3 projects from the front side of the inner wall 4 for electrical connection to a female terminal (not shown).
This terminal press-fitting construction in the connector 1 will be described in further detail. As shown in FIG. 9(a), the terminal press-fitting open hole 5 has an opening with a diameter .phi. when viewed in the direction of the axis of the open hole 5. As shown in FIG. 9(b), the press-fitting portion 3b of the male terminal 3 has a transverse cross-section (perpendicular to the axis of the male terminal 3) having a diameter .phi.'. The diameters .phi. and .phi.' are so determined that .phi.&lt;.phi.' is established, and the difference between the two diameters serves as a press-fitting amount, and the male terminal 3 is press-fitted and inserted into the terminal press-fitting open hole 5 while the press-fitting portion 3b forcibly expanding the terminal press-fitting open hole 5.
The male terminal 3 is held in intimate contact with the inner surface of the terminal press-fitting open hole 5 to form a seal therebetween, thereby preventing the leakage of the potting resin 7 (see FIG. 8).
Besides the terminal press-fitting construction employing the round pin-shaped terminals, there is also known a terminal press-fitting construction (as shown in FIGS. 10(a) and 10(b)) which includes terminal press-fitting open holes 8 of a rectangular cross-section (formed in a connector housing (not shown)), and tab-like male terminals 9 of a rectangular cross-section each for press-fitting into the associated terminal press-fitting open hole 8.
Namely, an opening of the terminal press-fitting open hole 8 has a rectangular cross-section when viewed in the direction of the axis of the open hole 8, and this open hole 8 has a width w1 and a thickness w2. The male terminal 9 has a width w3 and a thickness w4. These dimensions are so determined that w1&lt;w3 and w2&lt;w4 are established.
Therefore, the differences in these dimensions serve as a press-fitting amount, and as in the above terminal press-fitting construction (see FIG. 9), the male terminal 9 is press-fitted and inserted into the terminal press-fitting open hole 8 while forcibly expanding the terminal press-fitting open hole 8.
In the above conventional constructions, the terminal press-fitting open hole is forcibly expanded when press-fitting and inserting the male terminal thereinto, and therefore the operator is required to apply to the male terminal an inserting force larger than a compressive stress of a material (resin) of which the connector housing is made.
This inserting force acts on the terminal press-fitting open hole through the entire periphery of the male terminal, and therefore becomes a very large load, and when the inserting operation is effected for a long period of time, the efficiency of the operation is much lowered.
If the direction of press-fitting of the male terminal into the terminal press-fitting open hole does not fully coincide with the direction of application of the load by the operator, there is a possibility that the male terminal is deformed since the male terminal must be pressed into the terminal press-fitting open hole with a very large load as described above. This creates another cause of the lowered operation efficiency.
The sealing effect can be achieved by holding the male terminal and the inner surface of the terminal press-fitting open hole in intimate contact with each other, and therefore it is thought that the inserting force can be reduced by reducing the press-fitting amount as much as possible.
However, it is also necessary to provide the proper function of retaining the male terminal in position, and therefore in the above terminal press-fitting constructions, the press-fitting amount can not be reduced sufficiently regardless of the sealing effect.
Therefore, the above problems have not yet been solved, and there is still room for improvement.